Air conditioner

ABSTRACT

An air conditioner includes a switching valve, a flow rate restricting portion and an on-off valve. The switching valve provided in a flow path between a compressor and an outdoor heat exchanger. The outdoor heat exchanger includes a heat exchange portion and a heat exchange portion. During heating operation, the switching valve causes a second connection port, a third connection port and a first connection port to communicate with one another. The flow rate restricting portion and the on-off valve are connected in series between an outlet and an inlet of the compressor during the heating operation, to bypass a part of refrigerant. During defrosting operation of the heat exchange portion, the switching valve is configured such that a fourth connection port and the second connection port communicate with each other, and the third connection port and the first connection port communicate with each other.

CROSS REFERENCE TO RELATED APPLICATION

This application is a U.S. national stage application ofPCT/JP2017/023497 filed on Jun. 27, 2017, the contents of which areincorporated herein by reference.

TECHNICAL FIELD

The present invention relates to an air conditioner.

BACKGROUND ART

Japanese Patent Laying-Open No. 49-52343 (PTL 1) discloses a heatpump-type cooling and heating apparatus configured to, during heatingoperation, efficiently perform defrosting of an outdoor heat exchangeroperating as an evaporator, without stopping the heating operation.

CITATION LIST Patent Literature

PTL 1: Japanese Patent Laying-Open No. 49-52343

SUMMARY OF INVENTION Technical Problem

In the cooling and heating apparatus described in Japanese PatentLaying-Open No. 49-52343, a flow path switching valve is used, inaddition to a four-way valve. Japanese Patent Laying-Open No. 49-52343also describes that four solenoid valves are used in combination as theflow path switching valve. However, the solenoid valves are high inpressure loss.

Instead of the solenoid valves, an electric valve driven by a motor canalso be used. However, the electric valve is large in size. Therefore,reduction in size of the outdoor heat exchanger is difficult and themanufacturing cost is also high.

It is also conceivable to use, as the flow path switching valve, adifferential pressure driven-type valve capable of reducing a pressureloss, which is similar to a commonly-used four-way valve. In this case,however, it is necessary to prepare an introduction pipe configured tointroduce a suction-side pressure and a discharge-side pressure of acompressor required to drive the valve. Therefore, a pipe structure suchas routing of the introduction pipe becomes complicated and the numberof welded portions increases, which leads to lower workability duringmanufacturing.

Furthermore, airtightness and thermal insulation of buildings havebecome increasingly higher in recent years and very low-capacity heatingoperation is required after the room temperature is stabilized. Anoperation capacity of the compressor can be increased and decreased bychanging an operation frequency. However, a lower limit of the operationfrequency is set, and thus, the very low-capacity heating operationcannot be performed continuously and repeated operation and stop of thecompressor cause variation in room temperature.

The present invention has been made in light of the above-describedproblem, and an object of the present invention is to provide an airconditioner that makes it possible to reduce a lower limit capacity ofheating operation and to perform defrosting with a simple structurewithout stopping the heating operation.

Solution to Problem

An air conditioner according to the present disclosure is configuredsuch that refrigerant circulates through a compressor, an indoor heatexchanger, an expansion valve, and an outdoor heat exchanger in thisorder during heating operation. The air conditioner includes a switchingvalve, a flow rate restricting portion and an on-off valve. Theswitching valve is provided in a flow path between the compressor andthe outdoor heat exchanger. The outdoor heat exchanger includes a firstheat exchange portion and a second heat exchange portion, each of thefirst heat exchange portion and the second heat exchange portion havingan independent flow path.

The switching valve includes: a first connection port connected to aninlet of the compressor; a second connection port connected to the firstheat exchange portion; a third connection port connected to the secondheat exchange portion; and a fourth connection port connected to anoutlet of the compressor. During the heating operation, the secondconnection port, the third connection port and the first connection portcommunicate with one another, and do not communicate with the fourthconnection port. During defrosting operation of the first heat exchangeportion, the fourth connection port and the second connection portcommunicate with each other, and the third connection port and the firstconnection port communicate with each other.

During defrosting operation of the second heat exchange portion, thefourth connection port and the third connection port communicate witheach other, and the second connection port and the first connection portcommunicate with each other.

The flow rate restricting portion and the on-off valve are connected inseries between the outlet and the inlet of the compressor during theheating operation.

Advantageous Effects of Invention

The air conditioner according to the present disclosure can alternatedefrosting of the outdoor heat exchanger between the first heat exchangeportion and the second heat exchange portion, and can also operate in alow-capacity heating operation state.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a configuration diagram of an air conditioner 1 according to astudy example.

FIG. 2 is a configuration diagram of an air conditioner 201 according tothe present embodiment.

FIG. 3 is a block diagram for illustrating a connection relationship ofa controller in the air conditioner according to the present embodiment.

FIG. 4 shows a flow, a flow rate and a pressure of refrigerant in eachoperation mode of a flow path switching valve 202.

FIG. 5 shows a flow of the refrigerant in a normal heating operationmode.

FIG. 6 shows a flow of the refrigerant in a low-capacity heatingoperation mode.

FIG. 7 shows a flow of the refrigerant in a heating/defrosting operationmode.

FIG. 8 shows a flow of the refrigerant in a defrosting/heating operationmode.

FIG. 9 shows a flow of the refrigerant in a cooling operation mode.

FIG. 10 is a schematic cross-sectional view showing a configuration offlow path switching valve 202.

FIG. 11 shows positions of valve bodies of flow path switching valve 202and a flow of the refrigerant during heating operation.

FIG. 12 shows positions of the valve bodies of flow path switching valve202 and a flow of the refrigerant in the heating/defrosting mode (duringdefrosting operation of a heat exchange portion 40B).

FIG. 13 shows positions of the valve bodies of flow path switching valve202 and a flow of the refrigerant in the defrosting/heating mode (duringdefrosting operation of a heat exchange portion 40A).

FIG. 14 shows positions of the valve bodies of flow path switching valve202 and a flow of the refrigerant in the cooling mode.

DESCRIPTION OF EMBODIMENTS

An embodiment of the present invention will be described in detailhereinafter with reference to the drawings, in which the same orcorresponding portions are denoted by the same reference characters anddescription thereof will not be repeated.

A configuration of an air conditioner according to the presentembodiment will be described in comparison with a study example.

FIG. 1 is a configuration diagram of an air conditioner 1 according to astudy example. FIG. 2 is a configuration diagram of an air conditioner201 according to the present embodiment. First, components common toFIGS. 1 and 2 will be described.

Referring to FIGS. 1 and 2, air conditioner 1, 201 includes a compressor10, an indoor heat exchanger 20, an expansion valve 30, an outdoor heatexchanger 40, and a four-way valve 91 (291). Outdoor heat exchanger 40includes a heat exchange portion 40A and a heat exchange portion 40B.Heat exchange portion 40A and heat exchange portion 40B are formed, forexample, by vertically splitting outdoor heat exchanger 40 into twopieces.

A pipe 90 connects a port H of four-way valve 91 (291) and indoor heatexchanger 20. A pipe 92 connects indoor heat exchanger 20 and expansionvalve 30. A pipe 94 branches off partway into a pipe 94A and a pipe 94B,and connects expansion valve 30 and heat exchange portions 40A and 40B.

An outlet and an inlet of compressor 10 are connected to ports G and Eof four-way valve 91 (291), respectively. Pipes 97A and 97B connect heatexchange portion 40A and heat exchange portion 40B to a flow pathswitching portion 102 (FIG. 1) or a flow path switching valve 202 (FIG.2), respectively. A pipe 99 has one end connected to the outlet ofcompressor 10 and branches off partway into a pipe 100 and a pipe 101.Pipe 100 is provided with a flow rate restricting portion 104 at somepoint along pipe 100 and is connected to flow path switching portion 102(four-way valves 102A and 102B in FIG. 1) or flow path switching valve202 (a port C in FIG. 2). Pipe 101 connects pipe 99 and a port G offour-way valve 91 (291).

Expansion valve 30 is arranged at some point along a refrigerant pathformed of pipe 92 and pipe 94 that connect indoor heat exchanger 20 andoutdoor heat exchanger 40.

Air conditioner 1, 201 further includes a not-shown pressure sensor, anot-shown temperature sensor and a controller 300.

Compressor 10 is configured to change an operation frequency inaccordance with a control signal received from controller 300. Bychanging the operation frequency of compressor 10, an output ofcompressor 10 is adjusted. Various types of compressors can be used ascompressor 10, and a compressor of rotary type, of reciprocating type,of scroll type, of screw type or the like may be used, for example.

In the configuration shown in FIG. 1, a pipe 96 connects heat exchangeportion 40A and heat exchange portion 40B to a port F of four-way valve91, with flow path switching portion 102 being interposed. Duringheating operation, four-way valve 91 connects the outlet (pipe 101) ofcompressor 10 and pipe 90 as shown by a solid line, and connects theinlet (a pipe 98) of compressor 10 and pipe 96. During coolingoperation, four-way valve 91 connects the outlet of compressor 10 andpipe 96 as shown by a broken line, and connects the inlet of compressor10 and pipe 90.

In contrast, in the configuration shown in FIG. 2, a pipe 296 connectsheat exchange portion 40A and heat exchange portion 40B to pipe 98, withflow path switching valve 202 being interposed. During the heatingoperation, four-way valve 291 connects the outlet of compressor 10 andpipe 90 as shown by a solid line, and connects the inlet of compressor10 to pipe 100 with an on-off valve 204 being interposed. During thecooling operation, four-way valve 291 connects the outlet of compressor10 to pipe 100 with on-off valve 204 being interposed as shown by abroken line, and connects the inlet of compressor 10 to pipe 90.

In FIGS. 1 and 2, a direction of a flow of refrigerant during heating isshown by an arrow.

First, a basic operation of the heating operation will be described.During the heating operation, the refrigerant flows in the directionshown by the arrow. In FIG. 1, compressor 10 sucks the refrigerant frompipe 96 through four-way valve 91 and pipe 98 and compresses therefrigerant. In FIG. 2, compressor 10 sucks the refrigerant from pipe296 through pipe 98 and compresses the refrigerant. The compressedrefrigerant flows to pipe 90 through four-way valve 91.

Indoor heat exchanger 20 (condenser) condenses the refrigerant flowingfrom compressor 10 into pipe 90 through four-way valve 91 (291) andcauses the refrigerant to flow to pipe 92. Indoor heat exchanger 20(condenser) is configured to perform heat exchange (heat dissipation)between high-temperature and high-pressure superheated vapor(refrigerant) discharged from compressor 10 and the indoor air. As aresult of the heat exchange, the refrigerant is condensed and liquefied.Although not shown, an indoor unit fan is provided together with indoorheat exchanger 20 (condenser) and controller 300 adjusts a rotationspeed of the indoor unit fan in accordance with a control signal. Bychanging the rotation speed of the indoor unit fan, an amount of heatexchange between the refrigerant in indoor heat exchanger 20 (condenser)and the indoor air can be adjusted.

Expansion valve 30 decompresses the refrigerant flowing from indoor heatexchanger 20 (condenser) to pipe 92. The decompressed refrigerant flowsto pipe 94. Expansion valve 30 is configured such that the degree ofopening thereof can be adjusted in accordance with a control signalreceived from controller 300. When the degree of opening of expansionvalve 30 is changed in a closing direction, a refrigerant pressure onthe exit side of expansion valve 30 decreases and the degree of drynessof the refrigerant increases. On the other hand, when the degree ofopening of expansion valve 30 is changed in an opening direction, therefrigerant pressure on the exit side of expansion valve 30 increasesand the degree of dryness of the refrigerant decreases.

Outdoor heat exchanger 40 (evaporator) evaporates the refrigerantflowing from expansion valve 30 to pipe 94. The evaporated refrigerantflows to pipe 96 (or pipe 296) through flow path switching portion 102(or flow path switching valve 202). Outdoor heat exchanger 40(evaporator) is configured to perform heat exchange (heat absorption)between the refrigerant decompressed by expansion valve 30 and theoutdoor air. As a result of the heat exchange, the refrigerantevaporates into superheated vapor. A not-shown outdoor unit fan isprovided together with outdoor heat exchanger 40 (evaporator).Controller 300 adjusts a rotation speed of the outdoor unit fan inaccordance with a control signal. By changing the rotation speed of theoutdoor unit fan, an amount of heat exchange between the refrigerant inoutdoor heat exchanger 40 (evaporator) and the outdoor air can beadjusted.

During the heating operation as described above, frost may in some casesform on outdoor heat exchanger 40 and defrosting may be required. Insuch a case, it is conceivable to temporarily switch the operation tothe cooling operation and perform the defrosting operation for causingthe high-temperature compressed refrigerant to flow to outdoor heatexchanger 40. However, the heating operation is interrupted and thuscomfortableness in a room is compromised.

Accordingly, in the comparative example and the present embodiment,outdoor heat exchanger 40 is split into heat exchange portion 40A andheat exchange portion 40B, and defrosting is alternately performed. Flowpath switching portion 102 or flow path switching valve 202 is providedto allow the high-temperature and high-pressure refrigerant fromcompressor 10 to flow to the heat exchanger that performs defrosting.

However, flow path switching portion 102 according to the comparativeexample in FIG. 1 includes two valves, i.e., four-way valves 102A and102B. A differential pressure driven-type switching valve is widely usedas four-way valve 91 because ports E and F are fixedly connected to theinlet and the outlet of compressor 10 in both of cooling and heating anda pressure relationship is fixed.

In contrast, as to four-way valves 102A and 102B, pipe 96 is connectedto the inlet of compressor 10 and has a low pressure during heating,whereas pipe 96 is connected to the outlet of compressor 10 and has ahigh pressure during cooling. Therefore, four-way valves 102A and 102Bdo not have a port constantly supplied with a low pressure. In order touse common differential pressure driven-type switching valves asfour-way valves 102A and 102B, it is necessary to route another pipefrom pipe 98 to the vicinity of flow path switching portion 102.Therefore, the configuration of the example in FIG. 1 is complicated,and thus, there is room for improvement in reduction in size.Accordingly, in the present embodiment in FIG. 2, flow path switchingvalve 202 is provided, instead of flow path switching portion 102. Flowpath switching by flow path switching valve 202 of air conditioner 201according to the present embodiment will be described below.

FIG. 3 is a block diagram for illustrating a connection relationship ofthe controller in the air conditioner according to the presentembodiment. Referring to FIG. 3, a pressure sensor 52 detects a pressureof the refrigerant at an exit of outdoor heat exchanger 40 (evaporator)and outputs the detection value to controller 300. A temperature sensor54 detects a temperature of the refrigerant at the exit of outdoor heatexchanger 40 (evaporator) and outputs the detection value to controller300.

Controller 300 includes a CPU (Central Processing Unit), a memorydevice, an input/output buffer and the like (all are not shown), andcontrols four-way valve 291, flow path switching valve 202, on-off valve204, compressor 10, expansion valve 30 and the like in air conditioner201. The control can be processed not only by software but also bydedicated hardware (electronic circuit).

FIG. 4 shows a flow, a flow rate and a pressure of the refrigerant ineach operation mode of flow path switching valve 202. FIGS. 5 to 9 showa flow of the refrigerant in each operation mode. Each operation modewill be described with reference to FIG. 4. Hereinafter, for conveniencein distinction, a case of defrosting heat exchange portion 40A may bedenoted as “heating/defrosting operation mode”, and a case of defrostingheat exchange portion 40B may be denoted as “defrosting/heatingoperation mode”.

(1-1) In a normal heating operation mode, flow path switching valve 202is set such that a port B1, a port B2 and a port A communicate with oneanother and port C is cut off. The refrigerant flows from ports B1 andB2 to port A, and a state of the refrigerant at this time is, in oneexample, a gas-liquid two-phase state. Port A has a low pressure, portsB1 and B2 have a low pressure, and port C has a high pressure.

In four-way valve 291, the refrigerant flows from port G to port H. Onthe other hand, the refrigerant does not flow through port F and port Ebecause on-off valve 204 is closed although port F and port Ecommunicate with each other.

The flow of the refrigerant in the normal heating operation mode isshown in FIG. 5.

(1-2) In a low-capacity heating operation mode, flow path switchingvalve 202 is set such that port B1, port B2 and port A communicate withone another and port C is cut off, similarly to the normal heatingoperation mode. The refrigerant flows from ports B1 and B2 to port A,and a state of the refrigerant at this time is, in one example, agas-liquid two-phase state. Port A has a low pressure, ports B1 and B2have a low pressure, and port C has a high pressure.

In four-way valve 291, the refrigerant flows from port G to port H. Inaddition, in the low-capacity heating operation mode, the refrigerantflows from port F to port E because on-off valve 204 is open.

The flow of the refrigerant in the low-capacity heating operation modeis shown in FIG. 6.

(2-1) In the heating/defrosting operation mode, flow path switchingvalve 202 is set such that port A and port B1 communicate with eachother and port B2 and port C communicate with each other. Therefrigerant flows from port B1 to port A, and independently of thisflow, the refrigerant flows from port C to port B2. A state of therefrigerant flowing from port C to port B2 is, in one example, a gasstate. A state of the refrigerant flowing from port B1 to port A is, inone example, a gas state. Ports C and B2 have a medium pressure (wherehigh pressure>medium pressure>low pressure), and ports A and B1 have alow pressure.

The flow of the refrigerant in the heating/defrosting operation mode isshown in FIG. 7. Referring to FIG. 7, during defrosting of heat exchangeportion 40B in alternate defrosting, flow path switching valve 202 isset such that port A and port B1 communicate with each other and port B2and port C communicate with each other. Then, a part of thehigh-temperature and high-pressure refrigerant discharged fromcompressor 10 is decompressed and flows through heat exchange portion40B in a direction shown by an arrow. As a result, frost in heatexchange portion 40B melts. During that time, the liquid refrigerantfrom expansion valve 30 continues to flow through heat exchange portion40A. Heat exchange portion 40A operates as an evaporator, and thus, theheating operation in indoor heat exchanger 20 can be maintained.

(2-2) In the defrosting/heating operation mode, flow path switchingvalve 202 is set such that port A and port B2 communicate with eachother and port B1 and port C communicate with each other. Therefrigerant flows from port B2 to port A, and independently of thisflow, the refrigerant flows from port C to port B1. A state of therefrigerant flowing from port C to port B1 is, in one example, a gasstate. A state of the refrigerant flowing from port B2 to port A is, inone example, a gas state. Ports A and B2 have a low pressure, and portsB1 and C have a medium pressure.

The flow of the refrigerant in the defrosting/heating operation mode isshown in FIG. 8. Referring to FIG. 8, during defrosting of heat exchangeportion 40A in alternate defrosting, flow path switching valve 202 isset such that port A and port B2 communicate with each other and port B1and port C communicate with each other. Then, a part of thehigh-temperature and high-pressure refrigerant discharged fromcompressor 10 is decompressed and flows through heat exchange portion40A in a direction shown by an arrow. As a result, frost of heatexchange portion 40A melts. During that time, the liquid refrigerantfrom expansion valve 30 continues to flow through heat exchange portion40B. Heat exchange portion 40B operates as an evaporator, and thus, theheating operation in indoor heat exchanger 20 can be maintained.

(3) In a cooling operation mode, flow path switching valve 202 is setsuch that port B1, port B2 and port C communicate with one another andport A is cut off. The refrigerant flows from port C to ports B1 and B2,and a state of the refrigerant at this time is, in one example, a gassingle-phase state. Port A has a low pressure, ports B1 and B2 have ahigh pressure, and port C also has a high pressure.

The flow of the refrigerant in the cooling operation mode is shown inFIG. 9. Referring to FIG. 9, in the cooling mode, four-way valve 291 iscontrolled such that port F connected to on-off valve 204 and port Gcommunicate with each other and port E and port H communicate with eachother. In addition, in the cooling mode, on-off valve 204 is open. Therefrigerant discharged from compressor 10 flows through four-way valve291, on-off valve 204, flow path switching valve 202, and outdoor heatexchanger 40 to expansion valve 30, and then, returns to compressor 10through indoor heat exchanger 20.

FIG. 10 is a schematic cross-sectional view showing a configuration offlow path switching valve 202. Flow path switching valve 202 includesport A connected to the inlet of compressor 10, port B1 connected toheat exchange portion 40A, port B2 connected to heat exchange portion40B, and port C connected to the outlet of compressor 10.

Flow path switching valve 202 further includes a cylinder 460 having avalve body 452 sliding therein, a pilot valve 470 configured to switch apressure for driving valve body 452, a cylinder 410 having a valve body402 sliding therein, and a pilot valve 420 configured to switch apressure for driving valve body 402.

Valve body 452 is arranged in cylinder 460 and is configured to beslidable in an axial direction of cylinder 460. Partition members 454and 455 are provided on both sides of valve body 452. A first chamber456 is formed between partition member 454 and cylinder 460, and asecond chamber 457 is formed between partition member 455 and cylinder460. Due to a pressure difference between first chamber 456 and secondchamber 457, valve body 452 of the slide valve is driven. Valve body 452is configured to cause one of an intermediate port 411 and anintermediate port 412 to communicate with port B1 and close the other ofintermediate port 411 and intermediate port 412.

Valve body 402 is arranged in cylinder 410 and is configured to beslidable in an axial direction of cylinder 410. Valve body 402 isprocessed such that a central portion thereof has an inverted U shape.Due to the portion having the inverted U shape, valve body 402 connectsadjacent ports A and B2 or adjacent ports C and B2 such that therefrigerant can flow between adjacent ports A and B2 or between adjacentports C and B2. Valve body 402 is further provided with a through holecommunicating with intermediate port 411 or 412.

Partition members 404 and 405 are provided on both sides of valve body402. A third chamber 406 is formed between partition member 404 andcylinder 410, and a fourth chamber 407 is formed between partitionmember 405 and cylinder 410. Due to a pressure difference between thirdchamber 406 and fourth chamber 407, valve body 402 of the slide valve isdriven.

In a first state, valve body 402 causes intermediate port 411 tocommunicate with port A and port B2 and causes intermediate port 412 tocommunicate with port C. In a second state, valve body 402 causesintermediate port 412 to communicate with port B2 and port C and causesintermediate port 411 to communicate with port A.

Flow path switching valve 202 further includes pilot pipes 432, 433,434, 482, 483, and 484. Pilot pipe 432 connects chamber 406 to aswitching portion 421 of pilot valve 420. Pilot pipe 434 connectschamber 407 to switching portion 421 of pilot valve 420. Pilot pipe 482connects chamber 456 to a switching portion 471 of pilot valve 470.Pilot pipe 484 connects chamber 457 to switching portion 471 of pilotvalve 470.

Switching portion 421 and switching portion 471 are supplied with a highpressure from the outlet of compressor 10 by pilot pipe 433, and aresupplied with a low pressure from the inlet of compressor 10 by pilotpipe 483. Pilot valve 420 and pilot valve 470 switch connection ofswitching portion 421 and switching portion 471, respectively, using abuilt-in spring and a built-in electromagnet. As a result, one ofchambers 406 and 407 of cylinder 410 has a low pressure and valve body402 slides toward the chamber having a low pressure. Similarly, one ofchambers 456 and 457 of cylinder 460 has a low pressure and valve body452 slides toward the chamber having a low pressure.

Flow path switching valve 202 is configured to use the pilot pipes andpilot valves 420 and 470 smaller in size than the main pipes and themain valves, and switch the main valves using a pressure differencebetween the main pipes connected to the main valves. Therefore, in airconditioner 201, a pipe structure such as pipe routing is simple and thenumber of welded portions is small, which leads to high work efficiencyduring manufacturing.

Positions of the valve bodies of flow path switching valve 202 and aflow of the refrigerant will be described below with reference to FIGS.11 to 14 showing flow path switching valve 202 in a simplified manner.

FIG. 11 shows positions of the valve bodies of flow path switching valve202 and a flow of the refrigerant during the heating operation. Duringthe heating operation, valve body 452 moves in the right direction toclose intermediate port 412 and cause port B1 and intermediate port 411to communicate with each other. Valve body 402 moves in the leftdirection to cause ports A and B2 and intermediate port 411 tocommunicate with each other. As a result, during the heating operation,port B1, port B2 and port A communicate with one another and port C doesnot communicate with the other connection ports.

FIG. 12 shows positions of the valve bodies of flow path switching valve202 and a flow of the refrigerant in the heating/defrosting mode (duringthe defrosting operation of heat exchange portion 40B). Valve body 452moves in the right direction to close intermediate port 412 and causeport B1 and intermediate port 411 to communicate with each other. Valvebody 402 moves in the right direction to cause port B2 and port C tocommunicate with each other. As a result, during the defrostingoperation of heat exchange portion 40B, port C and port B2 communicatewith each other and port B1 and port A communicate with each other.

FIG. 13 shows positions of the valve bodies of flow path switching valve202 and a flow of the refrigerant in the defrosting/heating mode (duringthe defrosting operation of heat exchange portion 40A). Valve body 452moves in the left direction to close intermediate port 411 and causeport B1 and intermediate port 412 to communicate with each other. Valvebody 402 moves in the left direction to cause port B2 and port A tocommunicate with each other. As a result, during the defrostingoperation of heat exchange portion 40A, port A and port B2 communicatewith each other and port B1 and port C communicate with each other.

FIG. 14 shows positions of the valve bodies of flow path switching valve202 and a flow of the refrigerant in the cooling mode. Valve body 452moves in the left direction to close intermediate port 411 and causeport B1 and intermediate port 412 to communicate with each other. Valvebody 402 moves in the right direction to cause ports C and B2 andintermediate port 412 to communicate with each other. As a result, inthe cooling mode, port B1, port B2 and port C communicate with oneanother and port A does not communicate with the other connection ports.

Since the description of the state of flow path switching valve 202 ineach mode ends, air conditioner 201 described in the present embodimentwill be summarized with reference to FIGS. 2 to 4 again.

Air conditioner 201 according to the present embodiment is configuredsuch that the refrigerant circulates through compressor 10, indoor heatexchanger 20, expansion valve 30, and outdoor heat exchanger 40 in thisorder during the heating operation. Air conditioner 201 includes flowpath switching valve 202, flow rate restricting portion 104 and on-offvalve 204. Flow path switching valve 202 is provided in the flow pathbetween compressor 10 and outdoor heat exchanger 40.

Outdoor heat exchanger 40 includes heat exchange portion 40A and heatexchange portion 40B, each of heat exchange portion 40A and heatexchange portion 40B having an independent flow path.

Flow path switching valve 202 includes port A, port B1, port B2, andport C. Port A is connected to the inlet of the compressor. Port B1 isconnected to heat exchange portion 40A. Port B2 is connected to heatexchange portion 40B. Port C is connected to the outlet of compressor10, with flow rate restricting portion 104 being interposed.

Flow path switching valve 202 is configured such that port B1, port B2and port A communicate with one another and do not communicate with portC during the heating operation.

Flow path switching valve 202 is configured such that port C and port B1communicate with each other and port B2 and port A communicate with eachother during the defrosting operation of heat exchange portion 40A(defrosting/heating mode).

Flow path switching valve 202 is configured such that port C and port B2communicate with each other and port B1 and port A communicate with eachother during the defrosting operation of heat exchange portion 40B(heating/defrosting mode).

Flow rate restricting portion 104 and on-off valve 204 are connected inseries between the outlet and the inlet of compressor 10 during theheating operation. On-off valve 204 is controlled to be opened andclosed during the heating operation. A heating capacity of airconditioner 201 when on-off valve 204 is in an open state is lower thana heating capacity of air conditioner 201 when on-off valve 204 is in aclosed state. This is because a part of the high-temperature andhigh-pressure refrigerant is bypassed along the path through on-offvalve 204 as shown in FIG. 6.

With the above-described configuration, defrosting of outdoor heatexchanger 40 can be performed without interrupting the heatingoperation. In addition, by opening on-off valve 204, a part of thehigh-temperature and high-pressure refrigerant is bypassed withoutpassing through the heat exchangers, and thus, the low-capacity heatingoperation can also be performed.

Preferably, air conditioner 201 further includes four-way valve 291.Four-way valve 291 is configured to, during the heating operation,connect the outlet of compressor 10 to indoor heat exchanger 20 andconnect the inlet of compressor 10 to the outlet of compressor 10 withon-off valve 204 and flow rate restricting portion 104 being interposed.Four-way valve 291 is configured to, during the cooling operation,connect the outlet of compressor 10 to port C with on-off valve 204being interposed and connect the inlet of compressor 10 to indoor heatexchanger 20.

The flow path between on-off valve 204 and flow rate restricting portion104 is connected to port C.

Flow path switching valve 202 is configured such that port B1, port B2and port C communicate with one another and do not communicate with portA during the cooling operation.

With the above-described configuration, in the air conditioner capableof performing cooling and heating, defrosting of outdoor heat exchanger40 can be performed without interrupting the heating operation, and thelow-capacity heating operation can also be performed.

Preferably, flow path switching valve 202 further includes cylinder 460and cylinder 410. Cylinder 460 has valve body 452 sliding therein, valvebody 452 being configured to cause one of intermediate port 411 andintermediate port 412 to communicate with port B1 and close the other ofintermediate port 411 and intermediate port 412. Cylinder 410 has valvebody 402 sliding therein. Valve body 402 slides to thereby switch acommunication state in flow path switching valve 202 between the firststate and the second state. The first state is a state in whichintermediate port 411 communicates with port A and port B2 andintermediate port 412 communicates with port C. The second state is astate in which intermediate port 412 communicates with port B2 and portC and intermediate port 411 communicates with port A.

With the above-described configuration, even when switching is performedbetween the cooling operation and the heating operation, the highpressure side and the low pressure side are fixed in flow path switchingvalve 202. It is possible to implement a switching mechanism using thehigh and low pressures in the pipes connected to flow path switchingvalve 202 itself. Therefore, it is possible to implement compact flowpath switching valve 202 that is low in pressure loss and does not needto supply the valve body driving pressure to the switching valve byanother pipe. Since the valve in the circuit that allows continuousheating can be implemented using the pressure of the pipes connected tothe valve itself as a driving source, pipe routing of the airconditioner can become easier and the number of welded portions can bereduced.

It should be understood that the embodiment disclosed herein isillustrative and non-restrictive in every respect. The scope of thepresent invention is defined by the terms of the claims, rather than thedescription of the embodiment above, and is intended to include anymodifications within the scope and meaning equivalent to the terms ofthe claims.

REFERENCE SIGNS LIST

1, 201 air conditioner; 10 compressor; 20 indoor heat exchanger; 30expansion valve; 40 outdoor heat exchanger; 40A, 40B heat exchangeportion; 52 pressure sensor; 54 temperature sensor; 90, 92, 94, 94A,94B, 96, 97A, 97B, 98 to 101, 296 pipe; 91, 102A, 102B, 291 four-wayvalve; 102 flow path switching portion; 104 flow rate restrictingportion; 202 flow path switching valve; 204 on-off valve; 300controller; 402, 452 valve body; 404, 405, 454, 455 partition member;406, 407, 456, 457 chamber; 410, 460 cylinder; 411, 412 intermediateport; 420, 470 pilot valve; 421, 471 switching portion; 432 to 434, 482to 484 pilot pipe; A, B1, B2, C, E, F, G, H port.

The invention claimed is:
 1. An air conditioner configured such thatrefrigerant circulates through a compressor, an indoor heat exchanger,an expansion valve, and an outdoor heat exchanger in this order duringheating operation, the air conditioner comprising a switching valveprovided in a flow path between the compressor and the outdoor heatexchanger, the outdoor heat exchanger including a first heat exchangeportion and a second heat exchange portion, each of the first heatexchange portion and the second heat exchange portion having anindependent flow path, the switching valve including: a first connectionport connected to an inlet of the compressor; a second connection portconnected to the first heat exchange portion; a third connection portconnected to the second heat exchange portion; and a fourth connectionport connected to an outlet of the compressor, during the heatingoperation, the second connection port, the third connection port and thefirst connection port communicating with one another, and notcommunicating with the fourth connection port, during defrostingoperation of the first heat exchange portion, the fourth connection portand the second connection port communicating with each other, and thethird connection port and the first connection port communicating witheach other, during defrosting operation of the second heat exchangeportion, the fourth connection port and the third connection portcommunicating with each other, and the second connection port and thefirst connection port communicating with each other, the air conditionerfurther comprising a flow rate restricting portion and an on-off valveconnected in series between the outlet and the inlet of the compressorduring the heating operation, and a four-way valve configured to, duringthe heating operation, connect the outlet of the compressor to theindoor heat exchanger and connect the inlet of the compressor to theoutlet of the compressor with the on-off valve and the flow raterestricting portion being interposed, and configured to, during coolingoperation, connect the outlet of the compressor to the fourth connectionport with the on-off valve being interposed and connect the inlet of thecompressor to the indoor heat exchanger, wherein a flow path between theon-off valve and the flow rate restricting portion is connected to thefourth connection port, and the switching valve is configured such thatthe second connection port, the third connection port and the fourthconnection port communicate with one another and do not communicate withthe first connection port during the cooling operation.
 2. The airconditioner according to claim 1, wherein the switching valve furtherincludes: a first cylinder having a first valve body sliding therein,the first valve body being configured to cause one of a firstintermediate port and a second intermediate port to communicate with thesecond connection port and close the other of the first intermediateport and the second intermediate port; and a second cylinder having asecond valve body sliding therein, the second valve body beingconfigured to perform switching between a first state and a secondstate, the first state being a state in which the first intermediateport communicates with the first connection port and the thirdconnection port and the second intermediate port communicates with thefourth connection port, the second state being a state in which thesecond intermediate port communicates with the third connection port andthe fourth connection port and the first intermediate port communicateswith the first connection port.